Characterization and comparison of organic functional groups effects on electrolyte performance for vanadium redox flow battery

The vanadium redox flow battery with a safe and capacity-controllable large-scale energy storage system offers a new method for the sustainability. In this case, acetic acid, methane sulfonic acid, sulfonic acid, amino methane sulfonic acid, and taurine are used to overcome the low electrolyte energy density and stability limitations, as well as to investigate the effects of various organic functional groups on the vanadium redox flow battery. When compared to the pristine electrolyte (0.22 Ah, 5.0 Wh·L–1, 85.0%), the results show that taurine has the advantage of maintaining vanadium ion concentrations, discharge capacity (1.43 Ah), energy density (33.9 Wh·L–1), and energy efficiency (90.5%) even after several cycles. The acetic acid electrolyte is more conducive to the low-temperature stability of the V(II) electrolyte (177 h at ?25 °C) than pristine (82 h at ?2 °C). The –SO3H group, specifically the coaction of the –NH2 and –SO3H groups, improves electrolyte stability. The –NH2 and –COOH additive groups improved conductivity and electrochemical activity.